This invention relates generally to bicycles and other pedal vehicles. More particularly, it relates to a motor-assisted apparatus in the form of an assembly, or kit, which may be added to any existing bicycle to convert the bicycle from one which moves by pedal power alone to one which moves by pedal power, by motor-assisted power or by a combination of both. Use of this kit with a conventional bicycle serves to aid the bicyclist in negotiating steep gradients and other road situations with a lesser degree of effort given the normal physical conditions of the average bicyclist.
Bicyclists frequently encounter steep gradients and other road situations which can require exceptional physical strength to negotiate and which can be extremely difficult for cyclists who are not physically well trained. Such situations can over-burden the bicyclist""s muscles and cardiovascular system. In the experience of this inventor, there are a number of different applications which utilize auxiliary electrical motors added to a typical bicycle. For example, one such system affixes the electrical motor inside the wheel hub. This system requires that the electrical motor which is utilized be a small one, due to obvious space limitations. This, in turn, results in the motor providing a relatively low power level and a reduced static torque. It also results in an excessive weight burden on the wheel.
Another application known to this inventor affixes the electrical motor to the rear wheel axle of the bicycle. The electrical motor is utilized with a worm screw reduction gear which causes a considerable drop in efficiency under stress. Additionally, the motor and the batteries which are used in such an application create a considerable amount of weight on the bicycle""s rear axle. This tends to make the bicycle off-balance and renders any over-dimensioning of the bicycle chassis totally useless. Insofar as the bicycle chassis must carry out this difficult task, it results in further unbalancing of the bicycle""s manoeuverability.
Yet another application known to this inventor affixes the electrical motor between the bicycle""s pedals. In this fashion, the motor""s rotation axle is aligned generally perpendicularly to the bicycle pedals"" axle, with the 90xc2x0 return towards the transmission, by means of worm screws. This configuration makes it unfeasible for the motor to recover energy during braking of the bicycle. This is because the transmission""s worm screw decrease in revolutions allows the axle to effect a return rotation in a single direction only, i.e. from the motor to the wheel and not vice-versa. Additionally, the mounting of the motor in this fashion requires that only motors having a small circumference be used due to the problem posed by the limited space available. Such motors, in the experience of this inventor, have a very low torque and a low revolution rate.
Still another application known to this inventor affixes the motor with a direct hold on the wheel roller. In this fashion, the transmission roller is required to exercise great pressure on the bicycle""s tire, with resulting wearing down of the tire, and fairly high levels of wasted energy. Also encountered are problems related to clutch slippage such as where dust and water are present on the tire, a condition frequently encountered by bicyclists who travel on unpaved or wet roads.
It is, therefore, a principal object of this invention to provide a new, useful, and uncomplicated apparatus in the form of an assembly, or universal kit, which can be mounted to virtually any bicycle and which provides auxiliary electrical power to the bicyclist for reducing the need for exceptional physical strength on the part of the cyclist. It is another object to provide such an apparatus which utilizes the rate of pedal rotation and the pressure exerted by the cyclist on the bicycle pedals to actuate this auxiliary electrical power. It is yet another object of the present invention to provide such an apparatus which is discreet in appearance and does not interfere with the bicycle""s original aesthetics. It is still another object to provide such an apparatus which aids the cyclist in pedaling and which allows the cyclist to attain an autonomy of more than 35 kilometers or so which allows the cyclist to have a pleasant and serene bicycle ride. And it is yet another object of the present invention to provide such an apparatus which is easily assembled, which has a high level of efficiency in its use and which can be made such that its cost to the end user is relatively low.
The present invention has obtained these objects. It provides for a new, useful and uncomplicated assembly or kit which includes an electrical motor which is mountable to the pedal axle of a typical bicycle, the electric motor having permanent magnets, an electronic control for these motor magnets, batteries and a reduction gear based upon the motor""s number of revolutions per minute. The assembly also uses special sensors which register the pedal rotation rate and the pressure exerted by the bicyclist upon the pedals, which information is processed by a control device which controls actuation of the electric motor as such is required by the bicyclist. That is, the control notices how much current is being absorbed by the motor and reacts accordingly. For example, if the cyclist is riding slowly on level ground, the control reads this and sends very little energy to the motor as it is not needed. If, instead, the cyclist is on a steep incline, the number of rotations of the pedal may be the same as on level ground. However, the pressure exerted on the pedal by the cyclist is greater and the electronic control senses this additional pressure. Additional electric current is sent to the motor as more assistance is needed for the cyclist.
The assembly or kit of the present invention is also universal. That is, it can be easily affixed to any type of bicycle, regardless of whether it is presently in use or still remains to be built. The assembly or kit can be affixed to the gear box of the original pedals, with the electrical motor placed between the pedals and the rotation axle which allows the motor to have a larger circumference and, in turn, allows the device to achieve a considerable increase in low revolution torque. This lower number of revolutions is achieved by use of a chain reduction gear, both by the motor in relation to the return axle as well as in relation to the bicycle""s transmission rim. Use of the device does not alter the basis upon which any bicycle may be designed or built. That is, the device is fully functional notwithstanding the bicycle""s original cost, simplicity of construction or its level of efficiency. Furthermore, maintaining the bicycle""s original chain transmission system means that the cyclist can take advantage of the bicycle""s standard gear box ratio with a further gearing-down of the motor/wheel ratio.
A further advantage provided by the kit which is the subject of this invention is that it is functionally adapted to be attached to a single place on the bicycle. In this fashion, it can be made to oscillate and thus react, as previously alluded to, both to the pressure exerted on the pedals as well as to the counter-reaction of the rear wheel (by virtue of its resistant torque). This permits special sensors to interpret the situation to which the bicyclist finds himself or herself, namely, the type of start, the gradient, and the level area, thereby making the device take the appropriate action in real time by modulating the motor""s electrical current. Additionally, if the bicyclist wishes to increase his or her mileage autonomy, the cyclist can activate a pulley block by means of a magnetic friction on the return axle. This will enable the cyclist to recoup energy, both in braking as well as in climbing, insofar as the kinetic energy from the rear wheel to the motor will be transformed into electrical energy by the motor itself. This partially recharges the batteries, thus resulting in a decrease in the batteries"" electrical stress and a lengthening of their useful life. The foregoing and other features of the device of the present invention will be apparent from the detailed description which follows.